{"id":"CVE-2026-74540","state":"PUBLISHED","title":"Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp\n\nl2cap_le_connect_rsp() obtains a channel via\n__l2cap_get_chan_by_ident() but neither holds a reference nor uses\nl2cap_chan_hold_unless_zero() before locking and operating on it.\nA concurrent l2cap_chan_del() triggered by a remote disconnect can\nfree the channel between the lookup and l2cap_chan_lock(), causing\na use-after-free.\n\nThe BR/EDR counterpart l2cap_connect_rsp() and the sibling handler\nl2cap_le_command_rej() already use l2cap_chan_hold_unless_zero()\nto safely hold a reference, but l2cap_le_connect_rsp() was left\nunprotected.\n\nFix by adding l2cap_chan_hold_unless_zero() after the ident lookup\nand l2cap_chan_put() on the exit path, consistent with other L2CAP\nresponse handlers.","publishedAt":"2026-08-15T12:27:51.522Z","updatedAt":"2026-10-16T19:05:54.604Z","severity":{"score":8.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"15d6c2367217a6a20b1abae9f38ded716bf620f1","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"1818180fe12d6cec7a437bc59cde8efdf6b10250","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"8325eafb38c3dee5af329266393763693d17381b","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"fd4c1e301bdec60a40728ea37de531cbccda501a","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"522b730c62c53a1981604fd73524697fd347830d","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"58e3c5289ad230a7e24ae4b0c7b43f5ee6e32136","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"09f447accc2570751e7d17f0dc0788b40d3edade","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"c4740e7f23ff9a8210198d8b4703259e21b9f69d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bluetooth/l2cap_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.14","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bluetooth/l2cap_core.c"]}],"references":["https://git.kernel.org/stable/c/15d6c2367217a6a20b1abae9f38ded716bf620f1","https://git.kernel.org/stable/c/1818180fe12d6cec7a437bc59cde8efdf6b10250","https://git.kernel.org/stable/c/8325eafb38c3dee5af329266393763693d17381b","https://git.kernel.org/stable/c/fd4c1e301bdec60a40728ea37de531cbccda501a","https://git.kernel.org/stable/c/522b730c62c53a1981604fd73524697fd347830d","https://git.kernel.org/stable/c/58e3c5289ad230a7e24ae4b0c7b43f5ee6e32136","https://git.kernel.org/stable/c/09f447accc2570751e7d17f0dc0788b40d3edade","https://git.kernel.org/stable/c/c4740e7f23ff9a8210198d8b4703259e21b9f69d"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74540.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74540","state":"PUBLISHED","datePublished":"2026-08-15T12:27:51.522Z","dateUpdated":"2026-10-16T19:05:54.604Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.913Z"},"containers":{"cna":{"title":"Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp\n\nl2cap_le_connect_rsp() obtains a channel via\n__l2cap_get_chan_by_ident() but neither holds a reference nor uses\nl2cap_chan_hold_unless_zero() before locking and operating on it.\nA concurrent l2cap_chan_del() triggered by a remote disconnect can\nfree the channel between the lookup and l2cap_chan_lock(), causing\na use-after-free.\n\nThe BR/EDR counterpart l2cap_connect_rsp() and the sibling handler\nl2cap_le_command_rej() already use l2cap_chan_hold_unless_zero()\nto safely hold a reference, but l2cap_le_connect_rsp() was left\nunprotected.\n\nFix by adding l2cap_chan_hold_unless_zero() after the ident lookup\nand l2cap_chan_put() on the exit path, consistent with other L2CAP\nresponse handlers."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"15d6c2367217a6a20b1abae9f38ded716bf620f1","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"1818180fe12d6cec7a437bc59cde8efdf6b10250","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"8325eafb38c3dee5af329266393763693d17381b","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"fd4c1e301bdec60a40728ea37de531cbccda501a","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"522b730c62c53a1981604fd73524697fd347830d","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"58e3c5289ad230a7e24ae4b0c7b43f5ee6e32136","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"09f447accc2570751e7d17f0dc0788b40d3edade","versionType":"git"},{"version":"f1496dee9cbde2a62821f4441dadb0d3360f60c3","status":"affected","lessThan":"c4740e7f23ff9a8210198d8b4703259e21b9f69d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bluetooth/l2cap_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.14","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bluetooth/l2cap_core.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/15d6c2367217a6a20b1abae9f38ded716bf620f1"},{"url":"https://git.kernel.org/stable/c/1818180fe12d6cec7a437bc59cde8efdf6b10250"},{"url":"https://git.kernel.org/stable/c/8325eafb38c3dee5af329266393763693d17381b"},{"url":"https://git.kernel.org/stable/c/fd4c1e301bdec60a40728ea37de531cbccda501a"},{"url":"https://git.kernel.org/stable/c/522b730c62c53a1981604fd73524697fd347830d"},{"url":"https://git.kernel.org/stable/c/58e3c5289ad230a7e24ae4b0c7b43f5ee6e32136"},{"url":"https://git.kernel.org/stable/c/09f447accc2570751e7d17f0dc0788b40d3edade"},{"url":"https://git.kernel.org/stable/c/c4740e7f23ff9a8210198d8b4703259e21b9f69d"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:A - The vulnerability is reached when the kernel processes an incoming L2CAP LE Connect Response over an established Bluetooth LE ACL link (HCI ACL receive → l2cap_recv_acldata → l2cap_le_sig_channel → l2cap_le_connect_rsp), requiring radio proximity rather than routable Internet access.\nAC:L - The remote Bluetooth peer controls both sides of the race by sending L2CAP_LE_CONN_RSP while concurrently triggering channel teardown via L2CAP DISCONN_REQ or HCI disconnect, freeing the channel between __l2cap_get_chan_by_ident() and l2cap_chan_lock() without attacker-uncontrollable timing.\nPR:N - No local privileges on the victim are required; exploitation needs only a nearby attacker with an established LE Bluetooth connection sending crafted L2CAP signaling packets, with no root, CAP_NET_ADMIN, or user-namespace capability on the target host.\nUI:N - On phones, wearables, automotive, and IoT deployments, paired or background Bluetooth clients routinely auto-initiate L2CAP credit-based connections without per-attack user confirmation once an LE link is up, enabling trigger of the pending outgoing connect path.\nS:U - Impact is confined to kernel memory and privileges on the Bluetooth-connected host; there is no VM guest-to-host escape, sandbox breakout, or IOMMU/DMA boundary crossing, so security scope remains unchanged per kernel CVSS guidance.\nC:H - Use-after-free of heap-allocated struct l2cap_chan allows attacker-controlled reuse of freed slab memory, enabling disclosure of kernel heap contents and pointers through corrupted channel fields accessed after premature free.\nI:H - The UAF window writes channel state (ident, dcid, mtu, credits) and invokes chan->ops function pointers (ready, teardown) on freed memory, enabling heap spraying and control-flow hijack for arbitrary kernel code execution.\nA:H - Operating on a freed l2cap_chan can immediately kernel-oops or panic from corrupt mutex/state during lock/unlock and callback dispatch; UAF in softirq L2CAP processing inherently threatens full system availability."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-19T16:38:32.306Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"5.10.265"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.6.151"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.12.103"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.18.44"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"7.1.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74540","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:59:42.755795Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:05:54.604Z"}}]}}}